Stormwater Treatment: ST-12 - Detention Example for HEC-1 ... · ACTIVITY: Detention Example for HEC-1 & HEC-HMS ST – 12 Overview of Knoxville BMP Manual Stormwater Treatment ST-12

ACTIVITY: Detention Example for HEC-1 & HEC-HMS ST – 12

Knoxville BMP Manual www.knoxvilletn.gov/engineering/

Stormwater Treatment ST-12 - 1 May 2003

Description The purpose of this stormwater treatment BMP is to give a basic example of how to use

the HEC-1 and HEC-HMS hydrograph programs in detention basin routing and design.

The potential user of this BMP is expected to be thoroughly familiar with the TR-55

publication “Urban Hydrology for Small Watersheds” (reference 175) and also the theory

and practical application of detention routing. The detention example for this BMP is the

same one as used in ST-11 (Detention Example for Spreadsheet).

Approach

A brief description of detention requirements and NRCS methods are given in ST-10,

Detention Computations. All hydrologic and hydraulic computations for stormwater

detention facilities must be prepared and stamped by a registered engineer (licensed in the

state of Tennessee) who is proficient in this field. Plans must show sufficient information

to allow the builder to construct the detention structure correctly, and to verify that the

detention facility operates as required.

In Section 22.5-33 of the Knoxville Stormwater and Street Ordinance, hydrologic and

hydraulic computations are required to be in accordance with National Resources

Conservation Service (NRCS) methods. The NRCS Unit Hydrograph shall be used with

average antecedent moisture conditions (AMC II) and Type II rainfall distribution, as

specified by Technical Release 55 (TR-55) publication from June 1986. The TR-55

publication (“Urban Hydrology for Small Watersheds”, reference 175) can be

downloaded at:

http://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr55.html

NRCS Computational Software

A brief description of common hydrograph and detention routing software is given in ST-

10, Detention Computations. This BMP represents one option available to the stormwater

designer. Both HEC-1 and HEC-HMS are freely available software programs that can be

downloaded from the U.S. Army Corps of Engineers website. These programs can

generate hydrographs using several methods and also perform detention storage routing.

The program user generates the elevation-discharge-volume (E-Q-V) curves by manually

computing and analyzing each type of outlet device (by hand or with a spreadsheet)

separately prior to combining the results as input data for the hydrograph routing

program.

Software computations submitted for review to the City of Knoxville must include all of

the necessary input data to reproduce the detention design, including details as needed to

illustrate the outlet structure. Computations should be organized and neatly printed on

standard 8.5” x 11” paper so that the results are easily referenced and located. The

Knoxville Engineering Department may require verification of software programs that are

unproved or not well-known in the Knoxville area.

KK SUB01 Area 1 – Office

BA.00234

………(PH or PC cards)

LS 0 90

UD 0.067

KK RT01 Route through c

RS 1 ELEV 955

SA 0.000 0.005 0.012

SE 955 956 957

SQ 0.00 0.80 1.29

HEC

-1

http://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr55.html


Knoxville BMP Manual


Overview of

HEC-1

Software

Introduction

HEC-1 is a commonly-used hydrograph program originally developed by the U.S. Army

Corps of Engineers (USACE) over 30 years ago, and adapted to personal computers in the

mid-1980s. The HEC-1 program and the associated HEC-1 user’s manual can be

downloaded from the USACE website at:

http://www.hec.usace.army.mil/software/legacysoftware/hec1/hec1.htm

HEC-1 is a DOS-based program for which the user prepares an input data file prior to

running the program. Each line of the HEC-1 input file is called a “card” (from days

when computers used punched cards). See the example input file on page ST-12-8. The

first two letters of each line (columns 1-2) designate the type of data shown on that line.

The example input file on page ST-12-6 uses the following 16 types of cards:

ID = project identification, * = comments, IT = time specification

IN = input data interval, IO = output control, KK = location identifier,

BA = basin area, PB = basin total precipitation,

PC = cumulative precipitation, RS = storage routing, LS = loss rate,

UD = unit dimensionless hydrograph, SQ = discharge data,

SV = storage volume data, SE = elevation data, ZZ = end of run

Appendix A of the HEC-1 User’s Manual provides a complete description for the data

fields. It is recommended that the HEC-1 user should print the input card description for

each type of input card used. Each line contains up to 10 data fields with a maximum line

length of 80 spaces or columns. The data fields are in a “fixed-format” unless otherwise

specified by a *FREE card. The data fields each contain 8 spaces, except for the first

data field which only has 6 spaces (columns 3-8). Numbers should be right-justified

within each 8-space field and/or contain a decimal point.

The NRCS Type II rainfall distribution is entered on PC or PI cards; the example on page

ST-12-8 is shown using cumulative rainfall fractions (PC cards) at intervals of 0.1 hours.

Do not use PH cards to specify the intensity-duration-frequency curve, as this rainfall

pattern does not match the NRCS Type II rainfall distribution.

Postdeveloped watershed input parameters (area, curve number, time of concentration)

are entered on the BA, LS and UD cards. The basin area is entered as square miles on the

first field of the BA card. The curve number is entered on the second field of LS card.

Instead of the time of concentration, the lag time (in hours) is entered on the first field of

the UD card, with the lag time equal to 2/3 of Tc.

The overall elevation-discharge-volume (E-Q-V) relationship is entered on matching

fields of the cards labeled SE, SQ, and SV. The units for the E-Q-V curve are: feet

elevation (SE), cubic feet per second (SQ), and acre-feet (SV). The following pages show

an example of HEC-1 input file (for iteration #1 of the detention basin design *) and

HEC-1 output file (for iteration #2 of the detention basin design **):

Pages Contents of HEC-1 file File name .

ST-12-8 * Initial detention estimate HEC1-ex1.dat

ST-12-9 to ST-12-11 ** Final detention computation output HEC1-ex2.out

* Initial detention estimate corresponds to the example spreadsheet in ST-11.

** Final detention computation using the revised outlet configuration in ST-11.

HEC-1

input

“cards”

Worksheet #2

from ST-11 is

highly

recommended as

a starting point

for storage

volume estimates

http://www.hec.usace.army.mil/software/legacysoftware/hec1/hec1.htm




To improve the output precision of a HEC-1 run by a decimal point, perform these simple

modifications:

Multiply the basin area (BA card) by a factor of 10.

Multiply either the pond areas or pond volumes (SA or SV cards) by a factor of 10.

Multiply the pond outflows (SQ cards) by a factor of 10.

The example HEC-1 input file on page ST-12-8 includes the three modifications listed

above (shown in bold print), using SV cards rather than SA cards. After running the

HEC-1 file, the peak inflow and outflow values should be divided by 10 to determine the

actual output values.

Hints for

Using HEC-1

Example File

After downloading and installing the HEC-1 program, it will run by clicking on

the file HEC-1.EXE. As part of the HEC-1 program, a screen will pop up to ask

for the input filename, the output filename, and an optional DSS filename (which

is not needed). The input file needs to be in the same subdirectory as the HEC-1

program.

The input data files for the initial design configuration (hec1-ex1.dat) and for the

final outlet structure configuration (hec1-ex2.dat) are included in this BMP. The

input data file can be easily edited using any type of ASCII text editor (such as

Notepad). Align input data into the correct columns.

The following cards each only need one value changed: BA, PB, LS, UD, RS.

BA is the basin area in square miles, PB is the 24-hour rainfall in inches, LS is the

postdeveloped curve number, UD is the time of concentration multiplied by 0.67,

and RS is the starting water surface elevation of the analysis.

The following cards need to be recomputed and revised whenever the detention

basin volumes and/or outlet structure configuration are changed: SE, SQ, SV. A

new E-Q-V curve can be computed by hand or by spreadsheet. Provide a

sufficient number of values to accurately reflect the storage and discharge curves.

The HEC-1 output data is formatted by the program for the wide green computer

paper commonly used 30 years ago. To print onto 8.5” x 11” paper, shrink all of

the output text to Courier New, font size 8, with 0.25” margins all around the

page. Or print the results using paper with a landscape orientation.




Overview of

HEC-HMS

Software

Introduction

The HEC-HMS is a windows-based hydrograph program developed by the U.S. Army

Corps of Engineers (USACE) to succeed HEC-1. The HEC-HMS software program and

associated manuals can be downloaded from the USACE website at:

http://www.hec.usace.army.mil/software/software.html

Within the HEC-HMS program, the user creates three different types of components for

each modeling run:

Basin: size, precipitation loss functions, routing parameters, routing lengths

and channels, baseflow, reservoirs.

Meteorological: precipitation gages, rainfall distributions, storm events.

Control: duration of analysis, time intervals, computational increment.

Different basin configurations and outlet structures can be tested by mixing and matching

different components for a modeling run. After each modeling run, the routing results

can be displayed by selecting each element from the basin schematic and choosing “View

Results” from the menu. Graphical output and/or a global summary sheet can also be

viewed. The HEC-HMS program can import HEC-1 input files, which can be helpful in

preparing reports and graphs.

The current version of HEC-HMS will only allow the user to directly input one orifice

and one weir. For structures with more than one orifice, the user will have to compute the

elevation-storage-discharge data separately (by hand or by spreadsheet) prior to entering

the input data.

The HEC-HMS data interface can be confusing. For instance, sometimes it is not obvious

how to edit existing data files for the various components. For most screens, select the

file with the cursor and then choose “Edit” from the pulldown menu.

The HEC-HMS program is much more complicated than the HEC-1 program and will

require a longer learning curve to use effectively. For most engineers, it will take some

patience to learn how to use the HEC-HMS model. Read and review the available

training documents (Users Manual, Technical Reference Manual) while practicing with

the data sets provided by the U.S. Army Corps of Engineers.

The NRCS Type II rainfall distribution can be typed into the precipitation gage data fields

once, and then used over and over again for different projects by transfering gage data

into new project files as needed. The rainfall distribution can be adjusted on each model

run by choosing “Run Options” and then selecting a precipitation ratio.

Other Hints

for Using

HEC-HMS

Software

The program user must save each component as it is being edited, and also must

save the project file prior to exiting the HEC-HMS program.

The component with meteorological data, once it has been edited correctly, can be

used and reused for all project files. The total rainfall amount can be adjusted on

each model run by selecting “Run Options” from the Run Manager screen.

Each iteration (predeveloped & postdeveloped) can be run within the same basin

model (shown on page ST-12-12) by placing the design elements in parallel

alignment, reducing the number of basin files and components needed.

HEC-HMS

components

http://www.hec.usace.army.mil/software/software.html




Detention

Example

Input Data Needed

The initial volume estimate was made using Worksheet #2 (page ST-11-11), which is

based on NRCS methods outlined in the TR-55 publication. To summarize the watershed

parameters from ST-11:

Predeveloped CN = 75 Postdeveloped CN = 90

Predeveloped Tc = 0.4 hours Postdeveloped Tc = 0.1 hours

Predeveloped area = 1.5 acres Postdeveloped area = 1.5 acres

Volumes are computed from a rectangular detention basin with 3:1 slopes:

10’ x 60’ at elevation 955 First flush volume = 4500 cubic feet

25’ x 75’ at elevation 957.5 (from elevation 958.20 and below)

40’ x 90’ at elevation 960

52’ x 102’ at elevation 962

The initial outlet structure configuration was selected as a square concrete riser with four

circular orifices to limit postdevelopment flow rates to predevelopment flow rates:

4” orifice at invert 955.00




top of square concrete riser at 959.90 (total weir length of 8’)

This iteration was computed in the HEC-1 input data file on page ST-12-6, and similar

data was used within the HEC-HMS program. However, this outlet structure

configuration did not account for the first flush volume to be detained for a minimum of

24 hours, so a second iteration was required. The bottommost orifice is sized as 1.25”

diameter (page ST-10-9) to release the first flush volume (4500 cubic feet at the required

flow rate. A second outlet structure configuration (determined by trial and error) is:

1.25” orifice at invert 955.00




top of square concrete riser at 960.65 (total weir length of 8’)

Figure ST-12-1

Example Detention Basin Geometry

Elev 962.0 Freeboard (top of dam)

Elev 960.0 (40’ x 90’ = 3600 sq.ft.)

Elev 957.5 (25’ x 75’ = 1875 sq.ft.)

Elev 955.0 (10’ x 60’ = 600 sq.ft.) 3:1 side slopes

3:1 side slopes

18” RCP

NOT TO SCALE

Final outlet

structure

configuration

Initial outlet

structure

configuration




The second iteration was computed in the HEC-1 output file shown on pages ST-12-9

through ST-12-11. Both HEC-1 and HEC-HMS will require the user to first compute the

overall elevation-discharge-volume (E-Q-V) curve. The E-Q-V curve for this example

was taken from spreadsheets shown on pages ST-11-13 to ST-11-16 in the previous BMP.

After the stormwater detention computations are completed, an additional 15% storage

volume is provided. Multiply the 100-year peak flow storage volume by 115% to

determine an elevation adjustment value. Raise the top of the concrete riser (or other

principal outlet control) by this value to provide 15% additional storage volume. An

example of this computation is shown on page ST-10-8.

HEC-1

Results

Predevelopment Flows (HEC-1 Version 4.1, June 1998)

Time of

Return period Peak flow peak inflow

1-year 0.8 cfs 11.93 hours

2-year 1.6 cfs “ “

5-year 2.4 cfs “ “

10-year 3.2 cfs “ “

25-year 4.0 cfs “ “

100-year 5.2 cfs “ “

Iteration #1: HEC-1 Results (Version 4.1, June 1998)

Time of

Return period Peak inflow Peak outflow Target Peak WSE peak outflow

1-year 3.3 cfs 0.6 cfs 0.8 cfs 957.53 12.20 hours

2-year 4.9 cfs 1.2 cfs 1.6 cfs 958.24 12.17 “

5-year 6.4 cfs 2.3 cfs 2.4 cfs 958.73 12.10 “

10-year 7.8 cfs 3.1 cfs 3.2 cfs 959.11 12.10 “

25-year 9.2 cfs 3.8 cfs 4.0 cfs 959.47 12.10 “

100-year 11.1 cfs 5.1 cfs 5.2 cfs 959.90 12.10 “

Iteration #2: HEC-1 Results (Version 4.1, June 1998)

Time of


1-year 3.3 cfs 0.2 cfs 0.8 cfs 958.30 12.97 hours

2-year 4.9 cfs 1.2 cfs 1.6 cfs 958.81 12.17 “

5-year 6.4 cfs 2.3 cfs 2.4 cfs 959.31 12.10 “

10-year 7.8 cfs 3.1 cfs 3.2 cfs 959.72 12.10 “

25-year 9.2 cfs 3.7 cfs 4.0 cfs 960.11 12.10 “

100-year 11.1 cfs 5.4 cfs 5.2 cfs 960.58 12.10 “

HEC-HMS

Results

Predevelopment Flows (HEC-HMS Version 2.2.1, October 2002)

Time of

Return period Peak flow peak inflow

1-year 0.83 cfs 11:58 hours

2-year 1.60 cfs “ “

5-year 2.46 cfs “ “

10-year 3.27 cfs “ “

25-year 4.10 cfs “ “

100-year 5.34 cfs “ “

HEC-1 input file

without detention

for: A = 1.5 acres

CN = 75

Tc = 0.4 hours

(Results from the

HEC-1 input data file

on page ST-12-8.)

(Results from the

HEC-1 output data

file on pages ST-12-9

through ST-12-11.)

HEC-HMS input file

without detention for:

A = 1.5 acres

CN = 75

Tc = 0.4 hours




Iteration #1: HEC-HMS Results (Version 2.2.1, October 2002)

Time of


1-year 3.7 cfs 0.7 cfs 0.8 cfs 957.68 12:10 hours

2-year 5.3 cfs 1.4 cfs 1.6 cfs 958.34 12:08 “

5-year 6.9 cfs 2.5 cfs 2.5 cfs 958.82 12:06 “

10-year 8.3 cfs 3.3 cfs 3.3 cfs 959.19 12:06 “

25-year 9.7 cfs 4.0 cfs 4.1 cfs 959.54 12:06 “

100-year 11.6 cfs 5.3 cfs 5.3 cfs 959.96 12:06 “

Iteration #2: HEC-HMS Results (Version 2.2.1, October 2002)

Return period Peak inflow Peak outflow Target Peak WSE Time of peak


2-year 5.3 cfs 1.6 cfs 1.6 cfs 958.97 12:08 “

5-year 6.9 cfs 2.6 cfs 2.5 cfs 959.47 12:06 “

10-year 8.3 cfs 3.3 cfs 3.3 cfs 959.87 12:06 “

25-year 9.7 cfs 3.8 cfs 4.1 cfs 960.24 12:06 “

100-year 11.6 cfs 6.3 cfs 5.3 cfs X 960.64 12:04 “

By adding extra E-Q-V points at elevations 960.60, 960.70 and 960.80, the detention

routing computations for the 100-year storm (for iteration #2) become more accurate:


Conclusions The example software programs used in this BMP (HEC-1 and HEC-HMS hydrograph

routing) are able to generate inflow hydrographs and route them with a designed detention

basin. Many commercially available programs can also accomplish these same tasks.

Detention routing is necessary to verify that design estimates are adequate, particularly

since the initial volume estimate method within the TR-55 document does not take into

account the first flush volume requirements. Available detention space and configuration

must be included into a project site very early in the design process.

Comparison of

HEC-1 and

HEC-HMS

Programs

HEC-HMS has a few advantages over HEC-1 for detention routing analysis:

The NRCS Type II storm can be easily selected as a menu option, instead of

requiring to be input as a rainfall distribution with PC or PI cards.

Basin areas can be entered with more precision; therefore, the user does not have

to use the “multiply & divide by 10” procedure as per HEC-1 in order to add a

decimal point to the final answers.

U.S. Army Corps of Engineers is making adjustments/improvements to the HEC-

HMS program each year. Therefore, HEC-HMS will be state-of-the-art for many

years, while HEC-1 is no longer actively supported. Printing and checking

graphical displays is easier to accomplish using HEC-HMS.

The advantages of HEC-1 include:

The HEC-1 input data file (and/or output file) is easy to edit and contains all input

information in one location. A single data file is easier to archive, share and print

when compared to the multiple files used by HEC-HMS.

HEC-1 is not as complicated as HEC-HMS and is easier for occasional users to

learn and master.

References 153, 154, 158, 175, 180, 181, 186, 187, 200 (see BMP Manual Chapter 10 for list)

Knoxville Stormwater and Street Ordinance

(Using a HEC-HMS

project file similar

to input file on page

ST-12-8, but with an

embedded Type II

NRCS rainfall.)

(Using a HEC-HMS

project file similar

to pages ST-12-9 to

ST-12-11 with an

embedded Type II

NRCS rainfall.)

Adding more points

increases accuracy of

routing computation.




ID HEC-1 run for BMP Manual --- Initial volume estimate with the

ID ST-12, Detention Examples initial outlet structure configuration.

ID 10-YEAR 24-HOUR STORM

*

* This example problem has 1.5 acres, CN = 90, Tc = 0.1 hour.

* The basin area (BA), pond volumes (SV) and pond outflows (SQ) are

* multiplied by a factor of 10 to increase the precision of analysis.

* In other words, the basin area is input as 0.02344 square miles (15 acres).

* Detention basin is initially sized with spreadsheet ST-11 (Worksheet #2).

* City of Knoxville – Engineering Department – Ken Oliver

* May 1, 2003

* File: Hec1-ex1.dat

*

IT 2 01MAY03 0000 1500 2000

IN 6

IO 5 0

*

KK AREA1 Runoff into detention basin

BA.02344 * Basin area must be entered as square miles.

PB 4.8 * Total precipitation must be entered as inches.

PC 0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009

PC 0.010 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.020 0.021

PC 0.022 0.023 0.024 0.026 0.027 0.028 0.029 0.031 0.032 0.033

PC 0.034 0.036 0.037 0.038 0.040 0.041 0.042 0.044 0.045 0.047

PC 0.048 0.049 0.051 0.052 0.054 0.055 0.057 0.058 0.060 0.061

PC 0.063 0.065 0.066 0.068 0.070 0.071 0.073 0.075 0.076 0.078

PC 0.080 0.082 0.084 0.085 0.087 0.089 0.091 0.093 0.095 0.097

PC 0.099 0.101 0.103 0.105 0.107 0.109 0.111 0.113 0.116 0.118

PC 0.120 0.122 0.125 0.127 0.130 0.132 0.135 0.138 0.141 0.144

PC 0.147 0.150 0.153 0.157 0.160 0.163 0.166 0.170 0.173 0.177

PC 0.181 0.185 0.189 0.194 0.199 0.204 0.209 0.215 0.221 0.228

PC 0.235 0.243 0.251 0.261 0.271 0.283 0.307 0.354 0.431 0.568

PC 0.663 0.682 0.699 0.713 0.725 0.735 0.743 0.751 0.759 0.766

PC 0.772 0.778 0.784 0.789 0.794 0.799 0.804 0.808 0.812 0.816

PC 0.820 0.824 0.827 0.831 0.834 0.838 0.841 0.844 0.847 0.850

PC 0.854 0.856 0.859 0.862 0.865 0.868 0.870 0.873 0.875 0.878

PC 0.880 0.882 0.885 0.887 0.889 0.891 0.893 0.895 0.898 0.900

PC 0.902 0.904 0.906 0.908 0.910 0.912 0.914 0.915 0.917 0.919

PC 0.921 0.923 0.925 0.926 0.928 0.930 0.931 0.933 0.935 0.936

PC 0.938 0.939 0.941 0.942 0.944 0.945 0.947 0.948 0.949 0.951

PC 0.952 0.953 0.955 0.956 0.957 0.958 0.960 0.961 0.962 0.964

PC 0.965 0.966 0.967 0.968 0.970 0.971 0.972 0.973 0.975 0.976

PC 0.977 0.978 0.979 0.981 0.982 0.983 0.984 0.985 0.986 0.988

PC 0.989 0.990 0.991 0.992 0.993 0.994 0.996 0.997 0.998 0.999

PC 1.000

LS 0 90 * This is the postdeveloped curve number (CN=90).

UD .067 * This is the SCS lag time in hours (equal to 2/3 of Tc).

*

KK PONDA Route the hydrograph from Area 1 through Pond A

RS 1 ELEV 955.0 0

SV 0 0.0807 0.1876 0.3230 0.4886 0.6869 0.9196 1.1887 1.4964 1.8448

SV2.2358 2.6717 3.1543 3.6859 4.2685

SQ 0.00 2.4 3.8 4.9 5.7 6.4 7.7 17.2 29.0 38.2

SQ 53.8 164.2 198.0 208.0 218.0

SE 955.0 955.5 956.0 956.5 957.0 957.5 958.0 958.5 959.0 959.5

SE 960.0 960.5 961.0 961.5 962.0

ZZ




******************************************

* *

* FLOOD HYDROGRAPH PACKAGE (HEC-1) *

* U.S. ARMY CORPS OF ENGINEERS *

* JUN 1998 *

* HYDROLOGIC ENGINEERING CENTER *

* VERSION 4.1 *

* 609 SECOND STREET *

* *

* DAVIS, CALIFORNIA 95616 *

* RUN DATE 1MAY03 TIME 11:20:31 *

* (916) 756-1104 *

* *

******************************************

X X XXXXXXX XXXXX X

X X X X X XX

X X X X X

XXXXXXX XXXX X XXXXX X

X X X X X

X X X X X X

X X XXXXXXX XXXXX XXX

THIS PROGRAM REPLACES ALL PREVIOUS VERSIONS OF HEC-1 KNOWN AS HEC1 (JAN 73),

HEC1GS, HEC1DB, AND HEC1KW.

THE DEFINITIONS OF VARIABLES –RTIMP- AND -RTIOR- HAVE CHANGED FROM THOSE USED

WITH THE 1973-STYLE INPUT STRUCTURE.

THE DEFINITION OF -AMSKK- ON RM-CARD WAS CHANGED WITH REVISIONS DATED

28 SEP 81. THIS IS THE FORTRAN77 VERSION

NEW OPTIONS: DAMBREAK OUTFLOW SUBMERGENCE , SINGLE EVENT DAMAGE CALCULATION,

DSS:WRITE STAGE FREQUENCY

DSS:READ TIME SERIES AT DESIRED CALCULATION INTERVAL

LOSS RATE:GREEN AND AMPT INFILTRATION

KINEMATIC WAVE: NEW FINITE DIFFERENCE ALGORITHM

HEC-1 INPUT

LINE

ID.......1.......2.......3.......4.......5.......6.......7.......8.......9......10

1 ID HEC-1 run for BMP Manual --- Detention rating computations with the

2 ID ST-12, Detention Examples final outlet structure configuration

3 ID 10-YEAR 24-HOUR STORM Only the SQ cards have been changed.

*

* This example problem has 1.5 acres, CN = 90, Tc = 0.1 hour.

* The basin (BA), pond volumes (SV) and pond outflows (SQ) are

* multiplied by a factor of 10 to increase the precision of analysis.

* In other words, the basin area is input as 0.02344 square miles (15 acre

*

* Detention basin was initially sized using NRCS TR-55 methodology.

* City of Knoxville - Engineering Department - Ken Oliver

* May 1, 2003

* File: Hec1-ex2.dat

*

*DIAGRAM

4 IT 2 01MAY03 0000 1500 2000

5 IN 6

6 IO 5 0




*

* 1-year storm 2.5"

* 2-year storm 3.3"

* 5-year storm 4.1"

* 10-year storm 4.8"




*

7 KK AREA1 Runoff into detention basin

8 BA .02344 (= 15.0 acres, which is ten times the actual area of 1.5 acres)

9 PB 4.8

10 PC 0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009

11 PC 0.010 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.020 0.021

12 PC 0.022 0.023 0.024 0.026 0.027 0.028 0.029 0.031 0.032 0.033

13 PC 0.034 0.036 0.037 0.038 0.040 0.041 0.042 0.044 0.045 0.047

14 PC 0.048 0.049 0.051 0.052 0.054 0.055 0.057 0.058 0.060 0.061

15 PC 0.063 0.065 0.066 0.068 0.070 0.071 0.073 0.075 0.076 0.078

16 PC 0.080 0.082 0.084 0.085 0.087 0.089 0.091 0.093 0.095 0.097

17 PC 0.099 0.101 0.103 0.105 0.107 0.109 0.111 0.113 0.116 0.118

18 PC 0.120 0.122 0.125 0.127 0.130 0.132 0.135 0.138 0.141 0.144

19 PC 0.147 0.150 0.153 0.157 0.160 0.163 0.166 0.170 0.173 0.177

20 PC 0.181 0.185 0.189 0.194 0.199 0.204 0.209 0.215 0.221 0.228

21 PC 0.235 0.243 0.251 0.261 0.271 0.283 0.307 0.354 0.431 0.568

22 PC 0.663 0.682 0.699 0.713 0.725 0.735 0.743 0.751 0.759 0.766

23 PC 0.772 0.778 0.784 0.789 0.794 0.799 0.804 0.808 0.812 0.816

24 PC 0.820 0.824 0.827 0.831 0.834 0.838 0.841 0.844 0.847 0.850

25 PC 0.854 0.856 0.859 0.862 0.865 0.868 0.870 0.873 0.875 0.878

26 PC 0.880 0.882 0.885 0.887 0.889 0.891 0.893 0.895 0.898 0.900

27 PC 0.902 0.904 0.906 0.908 0.910 0.912 0.914 0.915 0.917 0.919

28 PC 0.921 0.923 0.925 0.926 0.928 0.930 0.931 0.933 0.935 0.936

29 PC 0.938 0.939 0.941 0.942 0.944 0.945 0.947 0.948 0.949 0.951

30 PC 0.952 0.953 0.955 0.956 0.957 0.958 0.960 0.961 0.962 0.964

31 PC 0.965 0.966 0.967 0.968 0.970 0.971 0.972 0.973 0.975 0.976

32 PC 0.977 0.978 0.979 0.981 0.982 0.983 0.984 0.985 0.986 0.988

33 PC 0.989 0.990 0.991 0.992 0.993 0.994 0.996 0.997 0.998 0.999

34 PC 1.000

35 LS 0 90

36 UD .067

*

37 KK PONDA

38 KM ROUTE HYDROGRAPH FROM AREA A THROUGH POND A

39 RS 1 ELEV 955.0 0

40 SV 0 0.0807 0.1876 0.3230 0.4886 0.6869 0.9196 1.1887 1.4964 1.8448

41 SV2.2358 2.6717 3.1543 3.6859 4.2685

42 SQ 0.0 0.3 0.4 0.5 0.6 0.6 0.7 3.0 17.0 27.0

43 SQ 35.2 41.5 119.4 208.0 218.0

44 SE 955.0 955.5 956.0 956.5 957.0 957.5 958.0 958.5 959.0 959.5

45 SE 960.0 960.5 961.0 961.5 962.0

46 ZZ

SCHEMATIC DIAGRAM OF STREAM NETWORK

INPUT

LINE (V) ROUTING (--->) DIVERSION OR PUMP FLOW

NO. (.) CONNECTOR (<---) RETURN OF DIVERTED OR PUMPED FLOW

7 AREA1




V

V

37 PONDA

(***) RUNOFF ALSO COMPUTED AT THIS LOCATION

****************************************

* *

* FLOOD HYDROGRAPH PACKAGE (HEC-1) *

* U.S. ARMY CORPS OF ENGINEERS *

* JUN 1998 *

* HYDROLOGIC ENGINEERING CENTER *

* VERSION 4.1 *

* 609 SECOND STREET *

* *

* DAVIS, CALIFORNIA 95616 *

* RUN DATE 1MAY03 TIME 11:20:31 *

* (916) 756-1104 *

* *

****************************************

HEC-1 run for BMP Manual --- Detention rating computations with the

ST-12, Detention Examples final outlet structure configuration

10-YEAR 24-HOUR STORM Only the SQ cards have been changed.

6 IO OUTPUT CONTROL VARIABLES

IPRNT 5 PRINT CONTROL

IPLOT 0 PLOT CONTROL

QSCAL 0. HYDROGRAPH PLOT SCALE

IT HYDROGRAPH TIME DATA

NMIN 2 MINUTES IN COMPUTATION INTERVAL

IDATE 1MAY 3 STARTING DATE

ITIME 0000 STARTING TIME

NQ 1500 NUMBER OF HYDROGRAPH ORDINATES

NDDATE 3MAY 3 ENDING DATE

NDTIME 0158 ENDING TIME

ICENT 20 CENTURY MARK

COMPUTATION INTERVAL .03 HOURS

TOTAL TIME BASE 49.97 HOURS

ENGLISH UNITS

DRAINAGE AREA SQUARE MILES

PRECIPITATION DEPTH INCHES

LENGTH, ELEVATION FEET

FLOW CUBIC FEET PER SECOND

STORAGE VOLUME ACRE-FEET

SURFACE AREA ACRES

TEMPERATURE DEGREES FAHRENHEIT

RUNOFF SUMMARY

FLOW IN CUBIC FEET PER SECOND

TIME IN HOURS, AREA IN SQUARE MILES

PEAK TIME OF AVERAGE FLOW FOR MAXIMUM PERIOD BASIN MAXIMUM TIME OF

OPERATION STATION FLOW PEAK 6-HOUR 24-HOUR 72-HOUR AREA STAGE MAX STAGE

HYDROGRAPH AT AREA1 78. 11.93 7. 2. 1. .02

ROUTED TO PONDA 31. 12.10 6. 2. 1. .02 959.72 12.10

*** NORMAL END OF HEC-1 ***




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Documents

Stormwater Treatment: ST-12 - Detention Example for HEC-1 ... · ACTIVITY: Detention Example for HEC-1 & HEC-HMS ST – 12 Overview of Knoxville BMP Manual Stormwater Treatment ST-12